T T E E C C H H N N I I C C A A L L M M A A N N U U A A L L ECLIPSE™ DESICCANT DRYERS ZPA HEATLESS MODELS T ABLE OF CONTENTS P AGE 1. INTRODUCTION 1 2. ABBREVIATED WARRANTY 1 3. HEATLESS DRYER NOMENCLATURE 2 4. RECEIVING AND INSPECTION 3 5. SAFETY AND OPERATION PRECAUTIONS 4 6. PRINCIPLES OF OPERATION 5 7. INSTALLATION / INITIAL START-UP 7 8. SCHEDULED MAINTENANCE 13 9. TROUBLESHOOTING 17 10. PURGE CHARTS 19 A TT ACHMENTS A. GENERAL ARRANGEMENT DRAWING B. WIRING DIAGRAM C. FLOW DIAGRAM D. SPARE PARTS LIST E. ENGINEERING SPECIFICATIONS ZEKS Compressed Air Solutions 1302 Goshen Parkway West Chester, Pennsylvania 19380 610-692-9100 800-888-2323 FAX 610-692-9192 WWW.ZEKS.COM COMPRESSED AIR SOLUTIONS TM ZPATM 90-5000 V0107
A. GENERAL ARRANGEMENT DRAWINGB. WIRING DIAGRAMC. FLOW DIAGRAMD. SPARE PARTS LISTE. ENGINEERING SPECIFICATIONS
ZEKS Compressed Air Solutions1302 Goshen Parkway
West Chester, Pennsylvania 19380610-692-9100 800-888-2323 FAX 610-692-9192
WWW.ZEKS.COM
COMPRESSED AIR SOLUTIONS TM
ZPATM 90-5000 V0107
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1. INTRODUCTION
ZEKS Eclipse™ Heatless Desiccant Dryers are designed to adsorb moisture fromcompressed air. The dryers are constructed with two towers, each containing desiccantbeads, that alternate between online (drying) and offline (regenerating) modes, yielding acontinuous stream of dry air at the dryer’s outlet. During normal operation, wet air passes through the on line tower and water vapor fromthe air is adsorbed (collected) on the desiccant beads. While air is being adsorbed in theonline tower, the moisture on the desiccant in the offline tower is removed by a processcalled desorption (regeneration). After an initial rapid depressurization, a portion of driedair from the online tower passes over the desiccant bed and carries the moisture off thebed and out the dryer’s exhaust.The continuous, alternating process of adsorption and desorption is controlled using atimer that switches the towers in a specific timed sequence. Very dry compressed air dewpoints are achieved through the continuous switching and operation of this dryer. ZEKSoffers dryers to provide either -40°F, -80°F or -100°F pressure dew point outlet air.
2. ABBREVIATED WARRANTY
ZEKS Eclipse™ heatless desiccant dryer products are warranted to be free from defectsin material and workmanship for a period of 12 months from the original date of shipmentfrom the factory. To allow the warranty to be in effect for 12 months from the date ofequipment start-up, the Warranty Registration Card must be completed and returned toZEKS. Alternately, the Warranty Registration Card may be completed online atwww.zeks.com. The total warranty period cannot exceed 18 months from the original dateof shipment from the factory.
Equipment must be installed and operated in accordance with ZEKS’ recommendations.ZEKS liability is limited to repair of, refund of purchase price paid for, or replacement inkind at ZEKS’ sole option, during the warranty time period stated above. IN NO EVENTSHALL ZEKS BE LIABLE OR RESPONSIBLE FOR INCIDENTAL OR CONSEQUENTIALDAMAGES, even if the possibility of such incidental or consequential damages has beenmade known to ZEKS Compressed Air Solutions. In addition, the usual maintenance andreplacement type products are not covered by this warranty.
The warranties expressed above are in lieu of and exclusive of all other warranties. Thereare no other warranties, expressed or implied, except as stated herein. There are noimplied warranties of merchantability or fitness for a particular purpose, which are specifi-cally disclaimed.
Valves – After the Basic Warranty noted above expires the diaphragm valves on the ZPAheatless dryers are warranted (parts only) for a total of 5 years from the date the dryer isshipped from the ZEKS factory. The following applies to this warranty:
a. Check valves are excludedb. Not applicable to dryers provided for -80 and -100 degree F dewpoint applicationsc. Valves must be rebuilt every two years. Refer to Section 8. of this manuald. Control line air filter element must be replaced once per year.
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3. HEATLESS DRYER NOMENCLATURE
NOMINALFLOWSCFM* TYPE / DESIGN SERIES ELECTRICAL POWER OPTIONS
90 ZPA= Pressure Swing 1 = 115-1-60 (-40°F)120 160200250300400 0= NEMA 1 0= STANDARD500 H= NEMA 4 A= FAIL TO SHIFT600 B= HIGH HUMIDITY800 C= A + B
1000 M= MOISTURE LOAD1200 CONTROL + A1500 N= M + B180021002700330040005000
* Nominal Flows indicated are for 100°F inlet temperature, 100°F ambient temperature and 100 psig compressed air pressure..
Nomenclature shown above represents standard price sheet options. Other options areavailable, refer to nomenclature insert specific to your dryer for details.
NOTICE
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4. RECEIVING AND INSPECTION
4.1 INSPECTIONUpon receiving your ZEKS air dryer, please inspect the unit closely. If roughhandling has been noticed, please note it on your delivery receipt, especially if thedryer will not be immediately uncrated. Obtaining the delivery person’s signedagreement to any noted damages will facilitate any insurance claims
4.2 UNPACKING AND HANDLING
Refer to labels on the dryer for the appropriate means for lifting or moving thedryer. For those dryers that indicate lifting via the structural skid, forks shouldextend all the way through the skid to reduce unnecessary forces to the dryerduring moving. When lifting the dryer, ensure that no stress is applied to the pipingor valving. Refer to Section 7.2 for locating and mounting of dryer.
NOTICE
Under no circumstances should any person attempt to lift heavyobjects without proper lifting equipment (i.e., crane, hoist, slings or forktruck). Lifting any unit without proper lifting equipment, can causeserious injury.
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5. SAFETY AND OPERATION PRECAUTIONS
Because an air dryer is pressurized and contains mechanical parts, the same precautionsshould be observed as with any piece of machinery of this type where carelessness inoperation or maintenance is hazardous to personnel. In addition to the many obvioussafety rules that should be followed with this type of machinery, the safety precautions aslisted below must be observed:
1. Only qualified personnel shall be permitted to adjust, perform maintenance or repair this air dryer.
OSHA HeadingDescription
2. Read all instructions completely before operating unit.
3. Pull main electrical disconnect switch and disconnectany separate control lines, if used, before attempting towork or perform maintenance on the unit.
4. Do not attempt to service any part while dryer is in an operational mode.
5. Do not attempt to remove any parts without first relievingthe entire air system of pressure.
6. Do not operate the dryer at pressures in excess of its rating.
7. Inspect unit daily to observe and correct any unsafe operating conditions.
The user of any air dryer manufactured by ZEKS Compressed Air Solutions, ishereby warned that failure to follow the above Safety and Operation Precautionscan result in personal injuries or equipment damage. However, ZEKS CompressedAir Solutions does not state as fact, nor does it mean to imply, that the precedinglist of Safety and Operating Precautions is all inclusive, and further, that theobservance of this list will prevent all personal injuries or equipment damage.
NOTICE
“Warning” is used to indicate ahazardous situation which hassome probability of death orsevere injury. Warning shouldnot be considered for propertydamage accidents unlesspersonal injury risk is present.
NOTICE“Notice” is used to indicate astatement of company policyas the message relates directlyor indirectly to the safety ofpersonnel or protection ofproperty. Notice should not beassociated directly with ahazard or hazardous situationand must not be used in placeof “Danger,” “Warning,” or“Caution.”
CAUTION
“Caution” is used to indicate ahazardous situation which mayresult in minor or moderateinjury.
WARNING
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6. PRINCIPLES OF OPERATION
6.1 INTRODUCTION
As described in Section 1, water vapor is removed from compressed air by divertingair flow alternately between two towers filled with desiccant. While one towerprocesses the compressed air stream, adsorbing water vapor, the opposite tower isregenerated by desorbing the water vapor and venting it to atmosphere. Refer to theProcess and Instrumentation Diagram (P&ID) for a visual representation of the dryingand regenerating cycles.
6.2 DRYING CYCLE
Saturated compressed air enters the dryer and is diverted to the appropriate towerby the Inlet Flow Valves. Referring to the Process and Instrumentation Diagram(P&ID), the Left Inlet Flow Valve is actuated to a closed position to prevent air flowfrom entering the regenerating tower. Simultaneously, the Right Inlet Flow Valve isactuated to an open position, allowing air flow to the right hand tower. During thistime, the Right Tower Purge Valve is actuated to a closed position, preventing thecompressed air from venting to atmosphere. As the compressed air flows throughthe desiccant material at pressure, removal of water vapor from the air stream beginsto occur through adsorption. In the adsorption process, the desiccant material drawswater vapor out of the compressed air and “holds” it until the right tower drying cycleis complete. Compressed air flows out of the tower for delivery to the process use.The Outlet Flow Check Valves provide air flow diversion to the outlet air connectionof the dryer. The Right Outlet Flow Check Valve allows air flow through to the outletconnection of the dryer while The Left Outlet Flow Check Valve checks off to preventflow back to the regenerating tower.
6.3 REGENERATION CYCLE
Previously adsorbed moisture, removed from the process stream, gets stripped ordesorbed from the desiccant material in the regeneration process. The first stage ofregeneration is tower depressurization. After the Inlet Flow Valves are switched todivert air flow away from the regenerating tower, the appropriate Purge Valve will beopened and the tower will be depressurized. Through rapid depressurization, asignificant portion of the previously adsorbed water vapor is stripped off of thedesiccant material and exhausted to atmosphere.
The second stage of regeneration uses a portion of the dry, compressed air,expanded to atmospheric pressure to complete the desorption process. As shown onthe P&ID, the compressed air exits the drying tower and a portion of the air flowsthrough the Purge Adjustment Valve and the Purge Orifice. Once the air has passedthrough Purge Orifice, it expands to atmospheric pressure and continues theregeneration process. Desorption occurs as the desiccant releases water vapor intothe regeneration air and is exhausted through the Purge Muffler.
Eclipse Heatless Dryers may be equipped with an optional Downstream Purgefeature. By adding additional check valves to the upper manifold, a dryer equippedwith the Downstream Purge option is able to use air from a downstream source topurge the regenerating tower. This optional feature is useful for applications withdownstream (dry) storage tanks, as pulling air from a downstream source canminimize cycling of the air compressor.
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6.4 SETTING THE REGENERATION AIR FLOW
Proper setting of the purge is necessary to achieve proper dryer performance.Setting the purge flow too high will waste compressed air and if set too low, the dryerwill not achieve proper dew point performance.
The purge adjustment manifold consists of the Purge Adjustment Valve, the PurgePressure Gauge and the Purge Orifice. When the right tower is the drying tower(pressurized) and the left tower is depressurized (0 PSIG), manually adjust thePurge Adjustment Valve until the gauge reading on the purge pressure gaugematches the Purge Pressure Gauge setting listed on the laminated tag affixed tothe Orifice Plate Assembly.
6.5 TOWER REPRESSURIZATION
Upon completion of tower regeneration, and prior to the Inlet Flow Valves changingposition to switch towers, the regenerated tower must be repressurized.
Repressurization is accomplished by closing the appropriate Purge Valve. Closingthe Purge Valve allows the regeneration air to begin to pressurize the tower. Inaddition to the regeneration air, the Repressurization Valve, (standard on -80°F and-100°F dew point and high pressure dryers; optional on -40°F dew point dryers)opens allowing some additional air from the outlet of the dryer to ensure adequatepressurization. During normal tower regeneration, the Repressurization Valve isheld closed so that the only source of air for regeneration passes through the purgeadjustment assembly.
Failure to re-pressurize prior to tower switchover will result in shocking thedesiccant material and cause premature desiccant dusting.
NOTICE
The right tower must be the drying tower for proper purge adjustment setting.When the left tower is the drying tower, the Purge Adjustment Gauge will readclose to line pressure.
NOTICE
On dryers equipped with the optional NEMA 4 / DPC™ Package or when using theoptional Moisture Load Control feature, the purge valve MUST be set to the factoryset point to insure proper operation of these features.
NOTICE
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6.6 VALVESSolenoid valves are used to actuate the Flow Valves, Purge Valves and the optionalRepressurization Valve on Eclipse Heatless Dryers. The Inlet Flow Valves andoptional Repressurization Valve are normally open valves, while the Purge Valvesare connected as nomrally closed valvaes. This arrangement permits air to flowthrough the dryer during periods of loss of power.
Outlet Check Valves are single direction check valves that will allow flow in thedirection shown on the P&ID, but not allow flow in the opposite direction.
6.7 TIMING SEQUENCEAll timing functions on NEMA 1 dryers are performed by the Solid State Timer(SST) and on NEMA 4 dryers by ZEKS DPC™ Controller. Regardless of controller,the timing of ZEKS -40°F, -80°F and -100°F dryers is as follows:
6.7.1 TIMING CYCLE FOR -40°F DEW POINT DRYERSThe standard timing cycle for -40°F operation switches the Inlet Flow Valveposition every five minutes which alternates the drying tower. At the sametime as a tower Inlet Valve opens, the appropriate tower Purge Valve opensto depressurize the regenerating tower. Tower regeneration occurs for 4minutes and 15 seconds, at which time the Purge Valve closes to initiaterepressurization.
6.7.2 TIMING CYCLE FOR AND -80°F and -100°F DEW POINT DRYERSThe standard timing cycle switches for both -80°F and -100°F operationswitches the Inlet Flow Valve position every 2 minutes which alternates thedrying tower. At the same time as a tower Inlet Valve opens, the appropriatetower Purge Valve opens to depressurize the regenerating tower. Towerregeneration occurs for 1 minute and 50 seconds, at which time the PurgeValve closes to initiate repressurization. The Repressurization Valve opensto assist tower repressurization for the last 10 seconds prior to Inlet FlowValve switching.
7. ALARMS AND INDICATORS
7.1 MOISTURE INDICATOR The moisture indicator senses a sample of the control air supply which is takenfrom the dryer outlet. The indicator provides an indication of dew point deteriora-tion at the outlet of the dryer. Under normal operating conditions, the indicator isblue. In the event of a dryer malfunction or prolonged dryer shut down, it will turngray in the presence of moisture.
7.2 FAILURE TO SHIFT ALARM (Optional)The Failure to Shift Alarm provides an indication of switching failure in one of thedryer switching valves. The Fail to Shift Alarm uses a pressure switch to monitorthe pressure in each tower.
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At “0” PSIG the switches are normally closed which sends a signal to the controller.When the towers pressurize, the switches open, thus removing the signal to thecontroller. The controller anticipates the appropriate open and closed switchposition based on its timing sequence. If either switch is in an incorrect position,the Failure to Shift Alarm light will illuminate on NEMA 1 dryers. Refer to the NEMA4 / DPC™ Package Supplement for NEMA 4 dryers equipped with the DPC™Controller.
7.3 HIGH HUMIDITY ALARM (Optional)The purpose of the High Humidity Alarm is to provide the operator an indication ifthe equipment fails to supply air at its designed dew point. This is accomplished bypassing a sample of dried air from the control line across a sensing element. If thesensing element is exposed to air with dew point of -10°F or higher (for -40°Fdryers), the sensor sends a signal to the humidistat. On NEMA 1 dryers, power isthen supplied to the red alarm light on the enclosure. This light will remain on untilthe problem is corrected and the sensing element has dried out. Refer to theNEMA 4 / DPC™ Package Supplement for NEMA 4 dryers equipped with theDPC™ Controller.
7.4 MOISTURE LOAD CONTROL (Optional)The Moisture Load Control (MLC) feature is designed to minimize the loss of purgeair during low flow or low water loading conditions. On -40 °F units, a sensorsamples the moisture content from the online tower and provides a signal to ahumidistat. As long as the humidistat finds that the air in each tower is dry, it willnot allow the controller to open the Purge Valves. Once the moisture content ineither tower is found to reach the threshold point, the humidistat sends a signal tothe controller and initiates the regeneration cycle. For -80°F & -100°F dryers, adigital dew point monitor is used in place of the humidistat. For dryers equippedwith the digital dew point monitor, refer to the Dew Point Monitor Addendum. ForNEMA 4 dryers equipped with ZEKS DPC™ Controller, refer to the NEMA 4 /DPC™ Package Supplement.
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7. INSTALLATION and START-UP
7.1 APPLICATION and CHECK ANALYSISTo achieve the best dryer performance, you should carefully check that the designand installation requirements outlined below are satisfied.
Operating pressure of ZEKS dryers can range from 75 -150 PSIG. Air available foryour usage will vary with operating pressure. The maximum design pressure of theZEKS Heatless Dryer is 150 PSIG. For units required for higher operatingpressures, consult your ZEKS representative.
The dryer must never be installed where air and/or ambient temperature exceeds120°F or drops below +50°F. Locate dryer to avoid extremes of heat and cold fromambient or other conditions. Avoid locating dryer outside or where it is exposed tothe elements.
7.2 LOCATING and MOUNTINGLift the dryer only by the lifting points indicated by the lifting labels on the dryer.
Bolt the dryer to the foundation using the bolt holes provided in the base frame. Anchor bolts should project a minimum of 3.5 inches above the foundation. Refer toGeneral Arrangement drawing for details.
7.3 PIPINGPipe the compressed air lines to the inlet and outlet connections. Locate theprefilters as close as possible to the dryer. Ensure the positioning allows for easeof servicing. Refer to the General Arrangement drawing.
Note that the wet air inlet is at the dryer’s lower manifold, while the dry air outlet isat the dryer’s upper manifold. In situations where air supply is required 24 hours aday (it is undesirable to interrupt the airflow), a three valve by-pass system isrecommended to bypass the dryer. Use the fewest elbows necessary to keeppressure drop at a minimum.
Once all piping has been connected, all joints including those on the dryer, shouldbe soap bubble tested at line pressure to ensure no joints have been damaged intransit and site placement.
The standard dryer is not rated for any gas other than air.
NOTICE
ZEKS recommends that the mufflers be cleaned after initial start-up to removeany desiccant dust generated during shipment. After running dryer for initial 30minute period, de-energize / depressurize dryer and remove mufflers.Disassemble and clean the removable insert inside the muffler core. Reinstallmufflers prior to operating dryer.
NOTICE
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7.4 FILTRATIONIt is important that a prefilter and an afterfilter be provided in your dryer installation.
Coalescing prefilters, located before the dryer, protect desiccant beds from contam-ination by oil, entrained water, pipe scale, etc., thereby, extending dryer desiccantlife. Locate prefilters as close to dryer as possible.
It is recommended that a mechanical separator be installed immediately precedingthe prefilter to remove the bulk liquid and entrained water.
Particulate afterfilters, located after the dryer, help eliminate the possibility ofdesiccant dusting and carryover into the air system.
7.5 ELECTRICAL CONNECTIONMake all electrical connections to the dryer as shown on the wiring diagram. Caremust be taken in connecting the proper voltages.
Size field connection knock-out for the conduit fitting required by the NEC.
7.6 DESICCANT LEVEL VERIFICATIONRemove desiccant fill port and the top of the desiccant vessel and check desiccantlevel. The level should be consistent with the level depicted on the Desiccant FillChart at the end of the manual
All dryers must have proper filtration. A .3 micron coalescing filter withautomatic drain & particulate after filter must be used as a minimum. Failure to
provide proper filtration for dryer will void warranty.
Dryer must be grounded with the full sized ground wire connected to an earthground.
Dryer must be fused according to NEC with the size fuse listed on the dryerserial nameplate, or on specification sheet in technical manual.
NOTICE
NOTICE
NOTICE
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7.7 START-UP
• Slowly pressurize the dryer. When the dryer reaches full operating pressure,check the system for air leaks. Soap test all joints and fitting. To maintain desireddew point, any leaks detected must be fixed, especially those on the outlet side ofthe dryer.
• Make sure that the purge adjustment valve is open and air outlet shut off valve (ifequipped) is closed.
• For dryers equipped with a dew point monitor, remove the dew point monitorsensor from the electrical enclosure and install in the sensing block, locatedbeside the enclosure and attach the sensor cable to the sensor.
• On dryers equipped with the Moisture Load Control option, verify that the MoistureLoad Control switch is in the OFF position to allow standard cycling at start-up.
• Turn on dryer disconnect switch (supplied by customer) to apply power to thedryer.
• For the first 30 seconds that the dryer is energized, both purge valves will remainclosed. After 30 seconds, the left tower purge valve will be opened and depres-surization of the left tower will occur.
• With a voltmeter, check the power connections for the correct voltage shown onthe dryer serial nameplate.
• Close and secure all electrical panel covers.
• When the dryer is energized, the Power-on Light and Right Tower Drying Light willbe illuminated. When electrical circuit has been energized, the Solid State Timerwill start automatically. See Section 6 for logic operating sequence.
• Following depressurization, adjust purge valve as described in Section 6.4
At initial start-up, check the dryer operation for one or two cycles, especially atthe time of the tower shift. Verify that all systems are operating in their properorder and sequence. If the dryer is not functioning properly, contact distributor orZEKS Technical Service.
NOTICE
For dryers equipped with the optional NEMA 4 / DPC™ Package, refer to theNEMA 4 / DPC™ Package Technical Manual Supplement prior to starting dryer.
NOTICE
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• If the dryer has been in storage or off for an extended period of time, the BlueMoisture Indicator may be gray, the High Humidity Alarm (if equipped) may beactivated and the dew point display (if equipped) may indicate a high dew point.Depending upon the duration of idle time, it may take anywhere from one totwelve hours for the alarm condition to go out, the BMI to return to its normal bluestate and the dew point to drop.
• Slowly open the outlet valve to gradually pressurize the down stream piping
• On dryers equipped with Moisture Load Control, the Moisture Load Control switchmay be turned “ON” to save purge air as described in Section 6.11.
When opening the outlet valve, insure drying tower gauge maintains linepressure. Allowing pressure to drop in the dryer will result in an overflowcondition.
NOTICE
-80° F and -100° F dryers require flow through the dryer to lower the pressuredew point to design levels. Failure to permit air flow through dryer (dead-heading) will result in elevated outlet dew points. Once air is permitted to flowthrough the dryer, the pressure dew point will gradually reduce to design levels.
NOTICE
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8. MAINTENANCE AND SYSTEM CHECK
8.1 SCHEDULED MAINTENANCE
DAILY MAINTENANCE FUNCTIONS:
•Check and record inlet pressure, temperature and flow. Verify that it is within specifications.
•Check tower pressure gauge readings within operating tolerance.
•Check operation for proper dryer cycling, depressurization and repressurization.
•Check that the prefilter drain is operating properly and that there is no condensatedischarged from purge mufflers.
•Verify that pressure in purging tower is 10 PSIG or less. If higher, muffler replace-ment is recommended. (Section 8.5)
•Verify that prefilter and afterfilter differential pressure is within operating limits.Change as required. (Section 8.2)
•Check the Blue Moisture Indicator. Make sure air is bleeding through the indicator.The indicator will be blue when air is dry.
SEMI-ANNUAL MAINTENANCE FUNCTIONS:
•Check outlet dew point.
•Check pilot air filter element and clean or replace as required.
•Replace prefilter and afterfilter elements and / or cartridges.
ANNUAL MAINTENANCE FUNCTIONS:
•Check desiccant and replace if necessary.
•Inspect and clean pilot air control solenoid valves, check valves and diaphragmvalves. Rebuild and / or replace as required.
•Test lights and switches, replace as necessary.
•Test electrical components, replace as necessary.
EVERY TWO YEARS:
•Replace diaphragm and seal kits on purge and switching diaphragm valves.
EVERY THREE - TO - FIVE YEARS:
•Replace desiccant.
•Rebuild purge and switching diaphragm valves (Preventative)
•Replace Check Valves (Preventative)
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8.2 Prefilters and Afterfilters• Prefilters - The cartridges of the prefilter must be changed as often as required to
prevent contamination of the regenerative dryer's desiccant bed.
The prefilter and automatic drain must be checked daily. To prolong filter cartridgelife, it is recommended that a mechanical air / moisture separator be placedimmediately before the prefilter.
• Afterfilters - The purpose of the afterfilter is to remove residual desiccant dust..Depending upon equipment application and usage, frequency of filter elementchange will vary. It is recommended to change filter element every six months asa minimum.
8.3 Pilot Air Control Solenoid ValvesThe length of time the pilot air valves can reliably operate without replacing isdependent upon the type of dryer and the dryer’s operation. On ZEKS -40°F dewpoint dryers, replacing the valves is recommended every 60 months. Given thedifference in cycle times for -80°F and -100°F units, these dryers should have theirpilot valves replaced every 30 months.
8.4 Muffler Changeout Procedure
• Depressurize the dryer turn control power off.
• Replace muffler.
• Follow Start-up procedure described in Section 7.6.
• Turn control power back on.
Should the drying system be overloaded and/or malfunctioning, causing highpressure drop, afterfilters will prematurely plug. This problem can be avoidedby frequent inspection and proactive replacement of cartridges.
NOTICE
To avoid injury, depressurize dryer before performing any service.
WARNING
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8.5 Purge and Switching Diaphragm Valves
These valves have two control ports; one on top and the other on the back side.
• Normally Open (N.O.) Valves: For N.O. inlet or repressurization valves, control airis supplied to the top port. The back side port exhausts out the bottom side of thediaphragm. If air leaks continuously when control air is supplied to the valve, theinternal seals are leaking and must be replaced.
• Normally Closed (N.C.) Valves: For N.C. purge valves, the top port is plugged.Control air is supplied to the back port. If air vents out of the back port continu-ously when the solenoid is de-energized, it will exhaust through the top of thesolenoid. If this condition is observed, the internal seals are leaking and must bereplaced.
8.6 Outlet Check Valves
Outlet check valves sealing can be verified by depressurizing the dryer and slowlyapplying pressure to the outlet. The valves should seal and prevent air frompressurizing the towers. If a tower begins to pressurize, the check valve on thatside requires replacement.
8.7 Desiccant Changeout Procedure
When it becomes necessary to replace the desiccant in the towers, or on units thatare shipped without the desiccant installed, observe the following procedure:
• The standard units are furnished with fill and drain ports on each desiccant tower.Remove the caps on both ports.
• To assist in getting the desiccant to flow from the tower, insert a small rod in to thedrain port as necessary. This may be required as the desiccant is packed into thetowers which may interfere with the desiccant flow from the towers.
To avoid injury, depressurize dryer before performing any service.
Be sure to wear respiratory protection during the draining and filling process tominimize inhalation of desiccant, as desiccant will produce dust during thisprocedure.
CAUTION
WARNING
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• Retainer screens, located at the inlet and outlet piping connections of the tower,are removable on all models. It is suggested that these screens be removed andcleaned at the time of desiccant changeout. These screens can be accessed bydisconnecting the upper and lower manifolds from the dryer towers.
• After cleaning the retainer screens, replace screens and reattach the outlet portplug.
• With the fill port plug removed, fill the dryer tower with the appropriate grade andsize desiccant. For those dryers that are shipped without desiccant installed,using the fill kit provided with the dryer will facilitate filling the desiccant in thetower. The level of the desiccant should be below the top retainer screen asshown on the Desiccant Fill Chart below.
• Once the towers have been filled, replace the fill port plug on each tower.
• Any connections disturbed in the desiccant changeout process should be leaktested prior to re-commissioning the dryer.
DESICCANT FILL CHART
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PROBLEM
Elevated dew point
Blue MoistureIndicator (BMI)indicates highmoisture level.
Excessive pressuredrop in dryer
Failure to shift
PROBABLE CAUSE
Insufficient purge rate.
Inlet air pressure belowdesign condition.
Flow rate higher than designcondition.
Inlet temperature abovedesign condition.(120°F)
Entrained water enteringdesiccant bed.
Desiccant contaminated by oil
Elevated dew point
BMI wet
Excessive flowrate.
Inlet pressure below designcondition.
No input power.
Defective solenoid valve.
No pilot air.
Pilot-operated diaphragmvalve seal failure
CORRECTIVE ACTION
Check purge flow settings.
Check purge piping for obstruction.
Clean purge piping and muffler.
Check pressure source and systemfor leakage.
Check flowrate and cause forincreased demand. Correct flowratecondition.
